1. Field of the Invention
The present invention relates to an apparatus for manufacturing compacted irons and an apparatus for manufacturing molten irons using the same, and more particularly, to an apparatus for manufacturing compacted irons by compacting reduced materials comprising fine direct reduced irons and manufacturing compacted irons and an apparatus for manufacturing molten irons using the same.
2. Description of the Related Art
The iron and steel industry is a core industry that supplies the basic materials needed in construction and in the manufacture of automobiles, ships, home appliances, etc. Further, it is an industry which has the longest history having advanced since the dawn of human history. Iron works, which play a pivotal roll in the iron and steel industry, produce steel from molten iron, and then supply it to customers, after first producing the molten iron (i.e., pig iron in a molten state) using iron ores and coals as raw materials.
Nowadays, approximately 60% of the world's iron production is produced using a blast furnace method that has been developed since the 14th century. According to the blast furnace method, irons ores, which have gone through a sintering process, and cokes, which are produced using bituminous coals as raw materials, are charged into a blast furnace together and oxygen is supplied to the blast furnace to reduce the iron ores to irons, thereby manufacturing molten irons. The blast furnace method, which is the most popular in plants for manufacturing molten irons, requires that raw materials have strength of at least a predetermined level and have grain sizes that can ensure permeability in the furnace, taking into account reaction characteristics. For that reason, cokes that are obtained by processing specific raw coals are needed as carbon sources to be used as fuel and as a reducing agent. Also, sintered ores that have gone through a successive agglomerating process are needed as iron sources. Accordingly, the modern blast furnace method requires raw material preliminary processing equipment, such as coke manufacturing equipment and sintering equipment. Namely, it is necessary to be equipped with subsidiary facilities in addition to the blast furnace, and also with equipment for preventing and minimizing pollution generated by the subsidiary facilities. Therefore, the heavy investment needed for the additional facilities and equipment leads to increased manufacturing costs.
In order to solve these problems with the blast furnace method, significant effort is made in iron works all over the world to develop a smelting reduction process that produces molten irons by directly using fine coals as fuel and as a reducing agent and by directly using fine ores, which account for more than 80% of the world's ore production.
An installation for manufacturing molten irons directly using raw coals and fine iron ores is disclosed in U.S. Pat. No. 5,534,046. The apparatus for manufacturing molten irons disclosed in U.S. Pat. No. 5,534,046 includes three-stage fluidized-bed reactors forming a bubbling fluidized bed therein and a melter-gasifier connected thereto. The fine iron ores and additives at room temperature are charged into the first fluidized-bed reactor and successively go through three-stage fluidized-bed reactors. Since hot reducing gas produced from the melter-gasifier is supplied to the three-stage fluidized-bed reactors, the temperature of the iron ores and additives is raised by contact with the hot reducing gas. Simultaneously, 90% or more of the iron ores and additives are reduced and 30% or more of them are sintered, and they are charged into the melter-gasifier.
A coal packed bed is formed in the melter-gasifier by supplying coals thereto. Therefore, iron ores and additives are melted and slagged in the coal packed bed and then are discharged as molten irons and slags. The oxygen supplied from a plurality of tuyeres installed on the outer wall of the melter-gasifier burns a coal packed bed and is converted to a hot reducing gas. Then, the hot reducing gas is supplied to the fluidized-bed reactors in order to reduce iron ores and additives and is exhausted outside.
However, since a high-speed gas flow is formed in the upper portion of the melter-gasifier included in the above-mentioned apparatus for manufacturing molten irons, there is a problem in that the fine reduced irons and sintered additives charged into the melter-gasifier are elutriated and loosened. Furthermore, when fine reduced irons and sintered additives are charged into the melter-gasifier, there is a problem in that permeability of gas and liquid in the coal packed bed of the melter-gasifier cannot be ensured.
In order to solve these problems, a method for briquetting fine reduced irons and additives and charging them into the melter-gasifier has been developed. Relating to the above development, U.S. Pat. No. 5,666,638 discloses a method for manufacturing oval-shaped briquettes made of sponge irons and an apparatus using the same. In addition, U.S. Pat. Nos. 4,093,455, 4,076,520, and 4,033,559 disclose a method for manufacturing plate-shaped or corrugation-shaped briquettes made of sponge irons and an apparatus using the same. Here, fine reduced irons are hot briquetted and then cooled, and thereby they are manufactured into briquettes made of sponge irons in order to suitably transport them a long distance.
A screw feeder arranged in a vertical direction is not suitable for manufacturing a large amount of briquettes made of sponge irons, but only for manufacturing a small amount of them. When briquettes made of sponge irons are manufactured by using the above method, if the charging amount of the fine reduced irons is increased in order to increase the manufacturing amount, fine reduced irons are not distributed well to a center portion of a longitudinal direction of the rolls, and thereby there is a problem in that the middle portion of a briquette is broken. In addition, since the length of the roll becomes longer as the roll for pressing and molding fine reduced irons is large-sized in a large-scaled installation, the charging amount of the fine reduced irons entering along the longitudinal direction of the rolls is not uniform, and a split phenomenon occurs. The split phenomenon means that the middle portion of a briquette made of sponge irons is broken. Therefore, a large amount of dust is produced when the briquettes are crushed in the next process.